Photovoltaic device and method for producing the same

Abstract

A photovoltaic device comprises a substrate having a plurality of conductive surfaces surrounded by an insulating surface, a plurality of first photovoltaic elements having single-crystal layer regions covering said conductive surfaces, and a second photovoltaic element covering said plurality of first photovoltaic elements. The single-crystal layer regions are separated from each other.

We claim: 
     
       1. A photovoltaic device comprising: a substrate having a plurality of mutually spaced conductive surfaces each surrounded by an insulating surface,   a first photovoltaic element having a single-crystal layer region covering each conductive surface thereby forming a plurality of first photovoltaic elements, and   a second photovoltaic element covering said plurality of first photovoltaic elements,   said single-crystal layer regions being separated from each other.   
     
     
       2. A photovoltaic device according to claim 1, wherein said second photovoltaic element comprises an amorphous material. 
     
     
       3. A photovoltaic device according to claim 1, wherein said second photovoltaic element has a layer region comprising a microcrystalline material. 
     
     
       4. A photovoltaic device according to claim 1, wherein the nucleation density of said conductive surfaces is greater than the nucleation density of said insulating surface and the size of said conductive surfaces is 4 μm or less in diameter. 
     
     
       5. A photovoltaic device according to claim 1, wherein materials of 4 μm or less in diameter having a nucleation density greater than said conductive surfaces and than said insulating surface are provided on said conductive surfaces. 
     
     
       6. A photovoltaic device according to claim 1, wherein said first photovoltaic element has a p-type semiconductor single-crystal layer and an n-type semiconductor single-crystal layer. 
     
     
       7. A photovoltaic device according to claim 1, wherein said second photovoltaic element has a p-type semiconductor non-single-crystal layer, an i-type semiconductor non-single-crystal layer and an n-type semiconductor non-single-crystal layer. 
     
     
       8. A photovoltaic device according to claim 1, further comprising a third photovoltaic element on said second photovoltaic element. 
     
     
       9. A photovoltaic device according to claim 8, wherein said third photovoltaic element has a semiconductor non-single-crystal layer. 
     
     
       10. A method for forming a photovoltaic device comprising: applying crystal growth treatment by vapor deposition to a substrate having a nonnucleation surface and a plurality of spaced apart nucleation surfaces having a nucleation density greater than said nonnucleation surface and a size sufficiently small so as to form only a single nucleus from which a single-crystal is grown,   forming a first photovoltaic element having a single-crystal layer region on each nucleation surface so that said single-crystal layer regions are isolated from each other thereby forming a plurality of first photovoltaic elements, and   forming a second photovoltaic element covering said plurality of first photovoltaic elements.   
     
     
       11. A method according to claim 10, wherein said nucleation surfaces comprise a surface of an underlying material and said nonnucleation surface is of a surface of an insulating layer. 
     
     
       12. A method according to claim 10, wherein said nonnucleation surface comprises a surface of an underlying material and of a surface of an insulating layer while said nucleation surfaces comprise a surface of a material having a nucleation density greater than said nonnucleation surface. 
     
     
       13. A photovoltaic device formed by the method for forming a photovoltaic device of claim 10.